Hitherto, culturing cells has been conducted on a surface of glass or a surface-treated synthetic polymer. For example, a polystyrene which has been subjected to a surface treatment, e.g. .gamma. ray irradiation, silicon coating etc., is used as a bed material for cell culture. Cultured cells on the bed are collected or detached from the surface of the bed by treating with a proteolysis enzyme (e.g. trypsin) or a chemical material (e.g. EDTA). In the treatment with a proteolysis enzyme or chemical material, however, the following problems occur: (1) the treating process is complicated and there is high possibility of introducing impurities. (2) The cultured or grown cells are adversely affected by the treatment and the treatment may harm their inherent functions.